Silicon carbide (SiC) is expected to be used as a material for a next-generation semiconductor device. SiC has the following excellent physical properties: a band gap is three times wider than that of silicon (Si); breakdown field strength is about ten times more than that of Si; and thermal conductivity is about three times more than that of Si. The use of these characteristics makes it possible to achieve a semiconductor device which has low power consumption and can operate at a high temperature.
An impurity diffusion coefficient in SiC is less than that of Si. Therefore, for example, even if a heat treatment is performed after impurities are introduced into SiC by ion implantation, it is difficult to drastically change an impurity profile by diffusion. For this reason, it is necessary to perform ion implantation with high accelerating voltage in order to form a deep pn junction in SiC using ion implantation.
However, there is a limitation to the accelerating voltage due to capability of an ion implantation apparatus. In addition, it costs a lot to perform ion implantation with high accelerating voltage.